The present invention relates generally to optical communications, and more particularly, to multi-service provisioning in orthogonal frequency division multiplexing-passive optical network OFDMA-PON.
The plethora of emerging service and network drivers is rapidly driving the next generation of passive optical networks (PON) beyond the standardized 10-Gigabit-capable passive optical network XG-PON and 10G Ethernet PON variants. These include time division, wavelength division, orthogonal frequency division, and code division multiple access solutions: time division multiple access TDMA, wavelength-division multiplexing WDM, orthogonal frequency division multiple access OFDMA, code division multiple access CDMA, respectively as well as hybrid options formed from the aforementioned constituent technologies.
However, while all these technologies operate on a point-to-multipoint PON topology, they often feature inherent and irreconcilable physical layer (PHY) differences. The resulting PHY divide poses both technical and practical difficulties in deploying multiple systems over a common fiber platform operated as a broadcast medium. Namely, with different PHY technologies running customized medium access control (MAC) protocols over a common wavelength channel, efficient yet fair inter-technology bandwidth allocation becomes a vital issue. Moreover, the cost-efficient mass market production of generic optical line terminal (OLT) interfaces also emerges as a challenge, since each network might need to support a different mix of heterogeneous optical network units (ONUs). Prominent examples include the co-existence of legacy and emerging PON technologies, as well as the open access environment, wherein multiple operators could deploy different technologies over a common infrastructure. In each case, a mechanism that makes optimal use of limited bandwidth resources and also bridges the PHY divide is required from both performance and cost perspectives.
Previously, a wavelength division multiplexing-passive optical network WDM-PON has been proposed to transparently deliver multiple services to a collection of ONUs, since each ONU can use a dedicated wavelength channel. However, a WDM-PON lacks the flexibility to dynamically allocate bandwidth resources among different services at increased granularity (only one wavelength can be used by each service). Therefore, a WDM overlay is appropriate only for enhancing the aggregate capacity in the access network, while other schemes are required for bandwidth allocation in the sub-wavelength domain. Sub-wavelength granularity could be achieved by using TDMA mechanisms similar to legacy PON. However, scaling up TDMA-PON beyond 10 Gb/s implies significantly increased complexity and cost for the optical components and the burst mode receivers at the OLT side.
Accordingly, there is a need for multi-service provisioning in orthogonal frequency division multiplexing-passive optical network OFDMA-PON.